1. Field of the Invention
This invention relates to a windowpane lifting mechanism for a vehicle door, and more particularly to a cable-type windowpane lifting mechanism for a vehicle door for lifting and lowering a windowpane of a vehicle door by way of a cable to open and close the window.
2. Description of the Prior Art
In an automobile, when lowering the windowpane of a front door into the door interior, the windowpane must be lowered first inclined forward in order to prevent interference with a door lock device disposed at a rear portion in the door panel and then gradually erected toward the original upright position in order to avoid collision of the front edge of the windowpane with a front wall portion of the door panel. Further, when lowering the windowpane of a rear door into the door interior, the windowpane must be lowered inclined forward in order to avoid interference with a wall portion defining a cutaway portion which is formed on the rear side of the door panel to accommodate a tire house. Such requirement on the action of the windowpane is especially significant in a hardtop type car in which the windowpane has a large area and no window sash is provided.
As a windowpane lifting mechanism, there has been in wide use a so-called X-link type windowpane lifting mechanism. For example, see Japanese Unexamined Utility Model Publication No. 57(1982)-88866. Generally, the X-link type windowpane lifting mechanism comprises a main arm member which is provided on the lower end thereof with a sector gear in mesh with a pinion supported on the door panel and the upper end of which is slidably connected to a windowpane holder mounted on the lower end of the windowpane, an auxiliary arm member which is pivoted on the main arm member, and is connected to the door panel for sliding movement at the lower end thereof and to the windowpane holder for sliding movement at the upper end thereof, and a guide rail member such as a sash for guiding the windowpane in up-and-down movement. In the lifting mechanism, the windowpane is moved up and down by rotation of the pinion by way of the main and auxiliary arm members.
Though being advantageous in that the windowpane can be held rigidly since a link mechanism is used, the X-link type windowpane lifting mechanism is disadvantageous in that the link mechanism occupies a large space in the internal space of the door to complicate the structure inside the door and to increase the overall weight of the same, and that the force required to lift and lower the windowpane varies with the vertical position of the windowpane.
On the other hand, there has been known a cable-type windowpane lifting mechanism as is disclosed, for instance, in Japanese Unexamined Utility Model Publication No. 58(1983)64778. The cable-type windowpane lifting mechanism comprises a cable member which is provided to vertically extend in the door interior and is connected to a lower end portion of the windowpane by way of a connecting member, and a guide rail member for guiding the windowpane in up-and-down movement. The windowpane is moved up and down to close and open the window by running the cable member upward and downward. The cable-type windowpane lifting mechanism is advantageous in that it is small in weight and occupies relatively small space in the internal space of the door and in that the force for lifting and lowering the windowpane is substantially constant. However, there arises a problem that in the cable-type windowpane lifting mechanism, the windowpane holding rigidity is relatively weak and accordingly it is difficult to move up and down the windowpane in an inclined state. Therefore, said requirement on the action of the windowpane during up-and-down movement is difficult to satisfy in the cable-type windowpane lifting mechanism.